Hitherto, there have been provided multi-room air-conditioning apparatuses, each of which includes a plurality of indoor units connected to a heat source unit (an outdoor unit) and is capable of selectively performing cooling or heating on each of the indoor units and is also capable of simultaneous execution of cooling on some indoor units and heating on other indoor units. For example, Patent Literature 1 discloses the following multi-room air-conditioning apparatus. A heat source unit is connected to a plurality of indoor units by first and second connection pipes via a relay unit. In the heat source unit, a switching valve that reduces the pressure in the first connection pipe and increases the pressure in the second connection pipe is provided between the first and second connection pipes. In the relay unit, the second connection pipe is connected to the plurality of indoor units via respective second flow control devices. Furthermore, pipes that connect the second connection pipe and the plurality of indoor units are connected to the first connection pipe via respective third flow control devices.
Patent Literature 2 discloses the following multi-room air-conditioning apparatus. In a heating operation, a gas-liquid separating device is provided on the inlet side of an outdoor-unit-side heat exchanger, and a gas refrigerant generated by gas-liquid separation is returned to a compressing element on the downstream side.
Patent Literature 3 discloses the following configuration. A heat-source-side gas-liquid separating device that separates a refrigerant into a gas refrigerant and a liquid refrigerant is provided in a heat source unit, and an injection pipe is connected to the heat-source-side gas-liquid separating device and is configured to return, to a compressing element on the downstream side through the injection pipe, the gas refrigerant generated by the gas-liquid separation performed by the heat-source-side gas-liquid separating device.
Patent Literature 4 discloses the following multi-room air-conditioning apparatus. A gas-liquid separating device is provided on the inlet side of an outdoor-unit-side heat exchanger, and, in a heating operation, a gas refrigerant generated by the gas-liquid separation performed by the gas-liquid separating device is supplied to the suction side of a compressor.